Method and apparatus for protecting wireless power receiver from excessive charging temperature

ABSTRACT

An apparatus and a method for protecting a wireless power receiver from excessive temperature caused by charging are provided. The apparatus includes a power receiver configured to receive wireless power in an alternate current (AC) form from a wireless power transmitter; a temperature measurement unit configured to measure a temperature of a point in the wireless power receiver during reception of the wireless power; and a controller configured to decrease a charging power corresponding to the wireless power, if a temperature measured by the temperature measurement unit exceeds a preset temperature, and to provide the charging power to a battery, if the temperature measured by the temperature measurement unit is lower than the preset temperature.

PRIORITY

This application is a Continuation of U.S. Ser. No. 14/099,228, whichwas filed in the U.S. Patent and Trademark Office on Dec. 6, 2013, andclaims priority under 35 U.S.C. §119(a) to a Korean Patent ApplicationSerial Nos. 10-2012-0141308 and 10-2013-0141403, which were filed in theKorean Intellectual Property Office on Dec. 6, 2012 and Nov. 20, 2013,respectively, the entire disclosure of each of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a method and an apparatus forprotecting a wireless power receiver from excessive temperature causedby charging.

2. Description of the Related Art

Mobile terminals, such as cell phones, Personal Digital Assistants(PDAs), and the like are powered by rechargeable batteries, and theyneed separate charging devices to recharge the batteries. Typically, thecharging device and the battery are electrically connected by contactingtheir contact terminals together.

However, such contact terminals are easily contaminated by dirt becausethey are exposed to the air, and thus battery charging may not beperformed correctly. Also, when the contact terminals are exposed tomoisture, charging may likely go wrong.

To solve this problem, wireless charging or contactless chargingtechnologies have recently been developed and applied to variouselectronic devices.

The wireless charging technology uses wireless power transmission andreception, which enables, for example, a battery of a cell phone to beautomatically charged just by placing the cell phone on a charging padwithout a need of a separate charging connector. This technology isknown in a form of wireless electric toothbrushes or wireless electricshaver. The wireless charging technology enhances waterproof performanceand portability of the electronic device by charging them wirelesslywithout a need of a cable charger, and in the field of electricvehicles, relevant technologies are expected to be significantlydeveloped.

In a wireless power receiver, rectifying alternate current power todirect current power and regulating the direct current power to acertain level may possibly create heat. The wireless power receivermonitors its temperature and stops receiving wireless power if thetemperature rises above a predetermined threshold. Thus, the wirelesspower receiver may stop wireless charging due to a temperature rise andresume it when the temperature drops. Considering the importance ofseamless wireless charging, the wireless power receiver may not performsuch seamless wireless charging once it stops charging due to a hightemperature until the temperature drops. To resume charging, it has tobe connected to a wireless power transmitter again and the user has towait until the connection is made, which may cause great inconvenienceto the user.

SUMMARY OF THE INVENTION

The present invention has been made to address at least the problems anddisadvantages described above, and to provide at least the advantagesdescribed below.

Accordingly, an aspect of the present invention is to provide anapparatus and a method for protecting a wireless power receiver fromexcessive temperature in order to keep the wireless power receiverperforming seamless charging.

Another aspect of the present invention is to provide an apparatus and amethod for preventing temperature rise in a wireless power receiver bydecreasing the current as the temperature rises above a presettemperature.

In accordance with an aspect of the present invention, a wireless powerreceiver is provided for preventing excessive temperature caused bycharging. The wireless power receiver includes a power receiverconfigured to receive wireless power in an alternate current (AC) formfrom a wireless power transmitter; a temperature measurement unitconfigured to measure a temperature of a point in the wireless powerreceiver during reception of the wireless power; and a controllerconfigured to decrease a charging power corresponding to the wirelesspower, if a temperature measured by the temperature measurement unitexceeds a preset temperature, and to provide the charging power to abattery, if the temperature measured by the temperature measurement unitis lower than the preset temperature.

In accordance with another aspect of the present invention, a method isprovided for protecting a wireless power receiver from excessivetemperature caused by charging. The method includes receiving wirelesspower from a wireless power transmitter; measuring a temperature of apoint in the wireless power receiver during reception of the wirelesspower; decreasing a charging power corresponding to the wireless power,if a temperature measured by the temperature measurement unit exceeds apreset temperature; and providing the charging power to a battery, ifthe temperature measured by the temperature measurement unit is lowerthan the preset temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will become more apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 illustrates a wireless charging system according to an embodimentof the present invention;

FIG. 2A is a block diagram illustrating a wireless power transmitter anda wireless power receiver according to an embodiment of the presentinvention;

FIG. 2B is a block diagram illustrating a wireless power receiveraccording to an embodiment of the present invention;

FIGS. 3A and 3B are block diagrams illustrating wireless power receiversaccording to various embodiments of the present invention;

FIG. 4 is a block diagram illustrating a wireless power receiveraccording to another embodiment of the present invention; and

FIGS. 5 and 6 are flowcharts illustrating a method of controlling awireless power receiver according to various embodiments of the presentinvention.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Various embodiments of the present invention will be described in detailhereinafter with reference to the accompanying drawings. This inventionmay, however, be embodied in many different forms and should not beconstrued as limited to the embodiments of the present invention setforth herein; rather, these embodiments of the present invention areprovided so that this invention will be thorough and complete, and willbe understood by those skilled in the art without departing from thescope of the invention. Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, third,etc., may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the scope of the present invention. Descriptionsshall be understood as to include any and all combinations of one ormore of the associated listed items when the items are described byusing the conjunctive term “˜ and/or ˜,” or the like.

The terminology used herein is for the purpose of describing particularembodiments of the present invention only and is not intended to limitthe invention. It is to be understood that the singular forms “a,” “an,”and “the” include plural references unless the context clearly dictatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms including technical and scientificterms used herein have the same meaning as commonly understood by one ofordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meanings in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

FIG. 1 illustrates a wireless charging system according to an embodimentof the present invention. Referring to FIG. 1, the wireless chargingsystem includes a wireless power transmitter 100 and at least onewireless power receiver 110-1, 110-2, . . . , 110-n.

The wireless power transmitter 100 may wirelessly transmit respectivepower 1-1, 1-2, . . . , 1-n to the at least one wireless power receiver110-1, 110-2, . . . , 110-n. The wireless power transmitter 100 maywirelessly transmit power 1-1, 1-2, . . . , 1-n to any of the wirelesspower receivers 110-1, 110-2, . . . , 110-n, which is authenticated in apredetermined authentication procedure.

The wireless power transmitter 100 may make electrical connection withat least one of the wireless power receivers 110-1, 110-2, . . . ,110-n. For example, the wireless power transmitter 100 may transmitwireless power to the at least one of the wireless power receivers110-1, 110-2, . . . , 110-n through electromagnetic waves.

The wireless power transmitter 100 may also perform two waycommunication with the at least one of the wireless power receiver110-1, 110-2, . . . , 110-n. The wireless power transmitter 100 and thewireless power receivers 110-1, 110-2, . . . , 110-n may handle orcommunicate packets 2-1, 2-2, . . . , 2-n of certain frames, which willbe described later in detail. The wireless power receiver may beimplemented particularly as a mobile communication terminal, a PersonalDigital Assistant (PDA), a Portable Multimedia Player (PMP), asmartphone, etc.

The wireless power transmitter 100 may provide wireless power to aplurality of the wireless power receivers 110-1, 110-2, . . . , 110-n.For example, the wireless power transmitter 100 may transmit wirelesspower to the plurality of the wireless power receivers 110-1, 110-2, . .. , 110-n in a resonance method. If the resonance method is adopted bythe wireless power transmitter 100, a distance between the wirelesspower transmitter 100 and any of the plurality of the wireless powerreceivers 110-1, 110-2, . . . , 110-n may be within less than 30 meters.Alternatively, if an electromagnetic induction method is adopted by thewireless power transmitter 100, a distance between the wireless powertransmitter 100 and any of the plurality of the wireless power receivers110-1, 110-2, . . . , 110-n may be within less than 10 cm.

At least one of the wireless power receivers 110-1, 110-2, . . . , 110-nmay charge a battery therein by receiving wireless power from thewireless power transmitter 100. Moreover, at least one of the wirelesspower receivers 110-1, 110-2, . . . , 110-n may transmit, to thewireless power transmitter 100, a signal to request wireless powertransmission, information to be used for wireless power reception,status information of the wireless power receiver, or controlinformation to control the wireless power transmitter 100, which will bedescribed later in detail.

Furthermore, at least one of wireless power receivers 110-1, 110-2, . .. , 110-n may transmit a respective message indicating a respectivecharging status to the wireless power transmitter 100.

The wireless power transmitter 100 may include a display means, such asa display unit, displaying the respective status of the wireless powerreceivers 110-1, 110-2, . . . , 110-n based on the respective messagesreceived from the wireless power receivers 110-1, 110-2, . . . , 110-n.The wireless power transmitter 100 may also display estimated time forcompletion of charging the respective wireless power receivers 110-1,110-2, 110-n. The wireless power transmitter 100 may also transmit acontrol signal (or control message) to each wireless power receiver110-1, 110-2, . . . , 110-n to disable its wireless charging function.Upon receiving the control signal to disable the wireless chargingfunction from the wireless power transmitter 100, the wireless powerreceiver may disable its wireless charging function.

FIG. 2A is a block diagram illustrating a wireless power transmitter anda wireless power receiver according to an embodiment of the presentinvention.

Referring to FIG. 2A, the wireless power transmitter 200 may include apower transmitter 211, a controller 212, and a communication unit 213.The wireless power receiver 250 may include a power receiver 251, acontroller 252, and a communication unit 253.

The power transmitter 211 may provide power requested by the wirelesspower transmitter 200, and wirelessly transmit power to the wirelesspower receiver 250. Here, the power transmitter 211 may supply power inan Alternate Current (AC) waveform, or may convert power in a DirectCurrent (DC) form into an AC waveform for supply through an inverter.The power transmitter 211 may also be implemented as a built-in batteryor as a power receiving interface for receiving external power andsupplying the power to other components in the wireless powertransmitter 200. People with ordinary skill in the art may readilyunderstand that the power transmitter 211 is not limited to what wasdescribed above but may be implemented with any means that may provideAC power.

In addition, the power transmitter 211 may transmit the AC power throughelectromagnetic waves to the wireless power receiver 250. The powertransmitter 211 may further include a loop coil to transmit or receivecertain electromagnetic waves. In the power transmitter 211, the loopcoil's inductance L may vary. People with ordinary skill in the art mayreadily understand that the wireless transmitter 211 may be implementedwith any means that may transmit or receive electromagnetic waves.

The controller 212 may control general operations of the wireless powertransmitter 200. The controller 212 may control the general operationsof the wireless power transmitter 200 by means of control algorithms,programs, or applications read from a storage. The controller 212 may beimplemented with a Central Processing Unit (CPU), microprocessor, ormini-computer. Detailed operation of the controller 212 will bedescribed later.

The communication unit 213 may communicate with the wireless powerreceiver 250 in a predetermined communication method. The communicationunit 213 may communicate with the communication unit 253 in the wirelesspower receiver 250 based on Near Field Communication (NFC), Zigbeecommunication, infrared communication, ultraviolet communication,Bluetooth communication, Bluetooth Low Energy (BLE), or the like. In theembodiment of the present invention, the communication unit 213 may usethe IEEE 802.15.4 Zigbee communication or BLE method. Moreover, thecommunication unit 213 may use the CSMA/CA algorithm Configuration ofselecting a frequency and a channel for use in the communication unit213 will be discussed later in detail. The aforementioned communicationmethods used by the communication unit 213 are just examples and are notlimited thereto.

The communication unit 213 may transmit a signal of information of thewireless power transmitter 200. Here, the communication unit 213 mayunicast, multicast, or broadcast the signal. Table 1 illustrates a datastructure of a signal transmitted from the wireless power transmitter200. The wireless power transmitter 200 may transmit a signal having thefollowing frame in every predetermined cycle. Here, the signal is dubbeda Notice signal.

TABLE 1 RX to Report Number frame protocol sequence network (schedule oftype version number ID mask) Reserved Rx Notice 4 bit 1 Byte 1 Byte 1Byte 5 bit 3 bit

Frame Type indicates a type of the signal, which is ‘Notice signal’ inTable 1. Protocol Version indicates a type of a protocol of thecommunication method, which may be assigned, e.g., 4 bits. SequenceNumber indicates a sequential order of the corresponding signal, whichmay be assigned, e.g., 1 byte. For example, Sequence Number may beincremented by 1 for each signal transmission or reception. Network IDindicates a network identifier of the wireless power transmitter 200,which may be assigned, e.g., 1 byte. Rx to Report (schedule mask)indicates which wireless power receiver does a report to the wirelesspower transmitter 200, which may be assigned, e.g., 1 byte. Table 2illustrates the Rx to Report (schedule mask) according to an embodimentof the present invention.

TABLE 2 Rx to Report (schedule mask) Rx1 Rx2 Rx3 Rx4 Rx5 Rx6 Rx7 Rx8 1 00 0 0 1 1 1

Rx1 through Rx8 may correspond to wireless power receivers 1 through 8,respectively. In the Rx to Report (schedule mask) illustrated in Table2, a wireless power receiver corresponding to ‘1’ may be intended to dothe report.

Reserved is a field reserved for later use, which may be assigned, e.g.,5 bytes. Number of Rx indicates the number of wireless power receiversaround the wireless power transmitter 200, which may be assigned, e.g.,3 bits.

The signal in the frame of Table 1 may be implemented in a form to beassigned to WPT of IEEE 802.15.4 data structure. Table 3 illustrates theIEEE 802.15.4 data structure.

TABLE 3 Preamble SFD Frame Length WPT CRC16

Referring to Table 3, the IEEE 802.15.4 data structure may includePreamble, SFD, Frame Length, WPT, and CRC16 fields, and the datastructure of Table 1 may correspond to the WPT field.

The communication unit 213 may receive power information from thewireless power receiver 250. The power information may include at leastone of capacity of the wireless power receiver 250, remaining amount ofthe battery, frequency of charging, battery consumption, batterycapacity, and battery charge/consumption ratio. The communication unit213 may transmit a charging function control signal to control acharging function of the wireless power receiver 250. The chargefunction control signal enables or disables the charging function bycontrolling the power receiver 251 in the wireless power receiver 250.

The communication unit 213 may receive signals not only from thewireless power receiver 250 but also from other wireless powertransmitters. For example, the communication unit 213 may receive fromthe other wireless power transmitter a Notice signal having the frame ofTable 1.

In FIG. 2A, the wireless power transmitter 200 includes the powertransmitter 211 and the communication unit 213 separately and usesout-band communications, but is not limited thereto. The powertransmitter 211 and the communication unit 213 may be integrated in asingle hardware device, and thus the wireless power transmitter 200 mayuse in-band communications.

The wireless power transmitter 200 and the wireless power receiver 250may communicate various signals with each other, and accordingly,subscription of the wireless power receiver 250 to a wireless powernetwork hosted by the wireless power transmitter 200 and chargingthrough wireless power transmission and reception may be performed,which will be described later in detail.

FIG. 2B is a block diagram illustrating a wireless power receiveraccording to an embodiment of the present invention.

Referring to FIG. 2B, the wireless power receiver 250 may include apower receiver 251, a controller 252, a communication unit 253, arectifier 254, a DC-to-DC converter 255, a switching unit 256, and acharging unit 257.

Description of the power receiver 251, controller 252 and communicationunit 253 will be omitted herein. The rectifier 254 may rectify wirelesspower received by the power receiver 251 into a DC form and beimplemented with e.g., bridge diodes. The DC-to-DC converter 255 mayconvert the rectified power with a predetermined gain. For example, theDC-to-DC converter 255 may convert the rectified power to 5 V at itsoutput end 259. Alternatively, lowest and highest voltages to be appliedto the front end (input end) of the DC-to-DC converter 255 may bepreset, which may be written in Input Voltage MIN and Input Voltage MAXfields of a Request Join signal, respectively, which will be discussedlater in detail. Rated voltage and rated current at the output end 259of the DC-to-DC converter 255 may also be written in Typical OutputVoltage and Typical Output Current fields of the Request join signal,respectively.

The switching unit 256 may connect the DC-to-DC converter 255 to thecharging unit 257. The switching unit 256 may be in an on or off stateunder control of the controller 252. The charging unit 257 may store thepower converted by the DC-to-DC converter 255 when the switching unit256 is in the on state.

FIG. 3A is a block diagram illustrating a wireless power receiveraccording to an embodiment of the present invention. Referring to FIG.3A, the wireless power receiver may include a power receiving unit 310and a terminal 320. The power receiving unit 310 may include a receivingcoil 311, a rectifier 312, a regulator 313, a temperature measurementunit 314, and a controller 315. The terminal 320 may include a PowerManagement Integrated Chip (PMIC) 321 and a battery 322. While it isassumed that a charger IC and Micro Control Unit (MCU) are integratedtogether in the PMIC 321 in FIG. 3A, the charger IC may be implementedseparately from the PMIC in another embodiment.

The receiving coil 311 is responsible for receiving wireless power froma wireless power transmitter. Wireless power in an AC form may beoutputted to the rectifier 312 from the receiving coil 311.

The rectifier 312 may convert the wireless power in the AC form into aDC form. The regulator 313 may regulate the wireless power in the DCform to a certain level. The regulator 313 may be configured with, e.g.,a DC-to-DC converter, regulating the wireless power to have a regulatedcurrent level. An input end of the regulator 313 may be connected to anoutput end of the rectifier 312, and an output end of the regulator 313may be connected to an input end of the PMIC 321 in the terminal 320.The regulator 313 may also receive from the controller 315 a controlsignal for current level regulation, as illustrated in FIG. 3A. In otherwords, a current outputted from the regulator 313 may be regulated basedon the control signal.

The temperature measurement unit 314 may start measuring temperature ofthe wireless power receiver in response to power transmission to thewireless power receiver. The temperature measurement may be performed ata predetermined first interval or non-periodically. Here, apredetermined first interval refers to a predetermined interval with afirst value for distinguishing the predetermined interval with othervalues. The temperature measurement unit 314 may measure a temperatureof a point in the wireless power receiver. For example, it may measure atemperature of at least one of the receiving coil 311, the rectifier312, the regulator 313, the PMIC 321, and the battery 322.

The controller 315 may control general operations of the power receivingunit 310. The controller 315 may also manage respective temperatureinformation of components of the power receiving unit 310, which isinputted from the temperature measurement unit 314. As to the currentlevel regulation, the controller 315 may regulate a current leveloutputted from the regulator 313 within a threshold. In an embodiment ofthe present invention the controller 315 may monitor a temperature at apoint inside of the wireless power receiver through the temperaturemeasurement unit 314, and may control the wireless power receiver to becharged with a regulated charging power if the monitored temperatureexceeds a preset temperature. In an embodiment of the present invention,the controller 315 may control the current flowing through either theregulator 313 or PMIC 321 to be decreased. The controller 315 mayregulate the charging power by providing a control signal to theregulator 313 to decrease the current outputted from the regulator 313to the PMIC 321, or alternatively, by providing a control signal to thePMIC 321 to decrease charging current from the PMIC 321 to the battery322.

For example, if a temperature of the rectifier 312 exceeds the presettemperature, the controller 315 may provide a control signal to theregulator 313 to decrease output current of the regulator 313. In otherwords, the controller 315 may provide a control signal to the regulator313 to decrease the charging current. The preset temperature is areference temperature set below an Over Temperature Protection (OTP)temperature that indicates an abnormal charging state, such asoverheating state.

The controller 315 may determine whether a temperature measured by thetemperature measurement unit 314 is higher than the preset temperature.If the measured temperature is higher than the preset temperature, itindicates that the wireless power receiver is being overheated due towireless charging and the charging status of the wireless power receivermay need to be carefully monitored.

For example, if the measured temperature is higher than the presettemperature, the controller 315 may provide a control signal to theregulator 313 to decrease the present current level to a predeterminedlevel. Alternatively, the controller 315 may divide a range between thepreset temperature and the OTP temperature into several sub-ranges, andmay provide a control signal to the regulator 313 depending on whatsub-range the measured temperature belongs to. A control signal fortemperature adjustment may be determined by referring to a predeterminedmapping table that shows relationships between measured temperatures andcurrents to be regulated. Accordingly, the controller 315 may determinehow and how much the temperature will be adjusted by referring to themapping table. Alternatively, if the measured temperature is above thepreset temperature, temperature measurement may be performed at apredetermined second interval. The predetermined second interval may beshorter than the predetermined first interval. Here, the predeterminedfirst and second interval refers to the predetermined interval having afirst and second value.

If a control signal for current level regulation is provided to decreasean output current of the regulator 313, a current passing through thePMIC 321 may also be decreased, thus eventually, temperature rise isprevented. The controller 315 may continually monitor temperature evenafter providing the control signal to decrease the output current. If ameasured temperature goes below the preset temperature, the controller315 may provide a control signal to increase the output current. On theother hand, if a measured temperature exceeds the preset temperature,the controller 315 may provide a control signal to decrease the outputcurrent. If a measured temperature is above both the preset temperatureand OTP temperature, it means that the wireless power receiver may bepossibly damaged by overheating. Thus, to protect the wireless powerreceiver from being damaged, the controller 315 may control a loadswitch to be off.

The PMIC 321 may manage the power received wirelessly or via cable, andthe power applied to respective components of the wireless powerreceiver. The PMIC 321 may control charging by regulating the powerprovided to the battery 322 for charging.

FIG. 3B is a block diagram illustrating a wireless power receiveraccording to another embodiment of the present invention. In contrast toFIG. 3A where the controller 315 regulates the output current of theregulator 313, FIG. 3B illustrates that the controller 315 may regulatean output current of the PMIC 321. For example, the controller 315 maydecrease the output current of the PMIC 321 if a measured temperatureexceeds the preset temperature. In such a way, the controller 315 maydecrease charging current flowing to the battery 322, therefore,temperature rise in the wireless power receiver is prevented. Regulationof an output current of the battery 322 may also be interpreted asregulating output power. In other words, for a constant voltage typebattery, current regulation leads to changes in power, so regulatingoutput current may lead to regulating output power.

The controller 315 may increase an output current of the PMIC 321 if ameasured temperature drops below the preset temperature. While someexamples of decreasing charging current or output current of theregulator 313 have been described, voltage may be decreased to apredetermined voltage level in other examples.

FIG. 4 is a block diagram illustrating a wireless power receiver,according to another embodiment of the present invention. Referring toFIG. 4, the wireless power receiver may include a receiving coil 410 anda terminal 420. The terminal 420 may include a rectifier 421, aregulator 422, a PMIC 423, a battery 424, a temperature measurement unit425, and a controller 426. In contrast to the wireless power receiverillustrated in FIG. 3B, in the wireless power receiver illustrated inFIG. 4, the terminal 420 may include the rectifier 421, the regulator422, the temperature measurement unit 425, and the controller 426. Therectifier 421, the regulator 422, the temperature measurement unit 425,and the controller 426 may be contained independently of the receivingcoil 410. Operations of the receiving coil 410, the rectifier 421, theregulator 422, the PMIC 423, the battery 424, and the temperaturemeasurement unit 425 are the same as or very similar to those of FIG.3B.

The PMIC 423 may convert a voltage of the regulated output power toanother voltage to be applied to other components of the terminal 420.For example, if the voltage of the regulated output power is 25V and aninput voltage of the battery 424 is 5V, the PMIC 423 may performDC-to-DC converting from 25V to 5V.

The battery 424 may be charged with wireless power using the convertedvoltage. The temperature measurement unit 425 may measure a temperatureof a component, such as the rectifier 421, the regulator 422, the PMIC423, the battery 424, etc., and provide the measurement result (i.e.,measured temperature) to the controller 426.

The controller 426 may control general operations of the terminal 420.In particular, the controller 426 may decrease output power of the PMIC423 based on the measured temperature of a component of the terminal420. For example, the controller 426 may decrease output power of thePMIC 423 if the measured temperature exceeds the preset temperature. Thecontroller 426 may increase output power of the PMIC 423 again if ameasured temperature drops below the preset temperature.

FIG. 5 is flowchart illustrating a method of controlling a wirelesspower receiver according to an embodiment of the present invention.

In step 510, the wireless power receiver may start wireless chargingwhile receiving wireless power from a wireless power transmitter. Instep 520, a temperature measurement unit in the wireless power receivermay measure a temperature of a point in the wireless power receiver. Thewireless power receiver may keep monitoring temperature of the wirelesspower receiver. If a measured temperature is lower than the presettemperature in step 530, the wireless power receiver may continuewireless charging in step 540. Otherwise, if the measured temperature ishigher than the preset temperature in step 530, the wireless powerreceiver may decrease charging current in step 550. For example, thewireless power receiver may decrease charging current of at least onecomponent included in the wireless power receiver.

In step 560, the wireless power receiver may determine again whether ameasured temperature is lower than the preset temperature. If themeasured temperature is lower than the preset temperature in step 560,the wireless power receiver may continue wireless charging. Otherwise,if the measured temperature is higher than the preset temperature instep 560, the wireless power receiver may decrease charging current instep 570. In step 580, the wireless power receiver may determine againwhether a measured temperature is lower than the preset temperature. Ifthe measured temperature is lower than the preset temperature, thewireless power receiver may continue wireless charging. The wirelesspower receiver illustrated in FIG. 5 may decrease a current valueapplied to the wireless power receiver. If the measured temperature ishigher than the preset temperature, i.e., if a temperature measuredafter a predetermined interval is still higher than the presettemperature, in step 590, the wireless power receiver may determine thattemperature has not yet been recovered to normal and may stop wirelesscharging.

FIG. 6 is flowchart illustrating a method of controlling a wirelesspower receiver according to an embodiment of the present invention.

In step 610, the wireless power receiver may start wireless chargingwhile receiving wireless power from a wireless power transmitter. Instep 620, a temperature measurement unit in the wireless power receivermay measure a temperature of a point in the wireless power receiver. Thewireless power receiver may keep monitoring temperature of the wirelesspower receiver. If a measured temperature is lower than the presettemperature in step 630, the wireless power receiver may continuewireless charging in step 640. Otherwise, if the measured temperature ishigher than the preset temperature in step 630, the wireless powerreceiver may re-set charging current based on a temperature difference(Δtemperature). The temperature difference may be a difference between ameasured temperature and the preset temperature. The wireless powerreceiver may pre-store information regarding relationships betweentemperature differences and charging currents to be re-set. The wirelesspower receiver may read out the information if a measured temperature islower than the preset temperature and re-set charging current based onthe information. For example, the wireless power receiver may re-setcharging power to be decreased.

In step 660, the wireless power receiver may compare again a measuredtemperature with the preset temperature. If the measured temperature islower than the preset temperature in step 660, the wireless powerreceiver may continue wireless charging with the re-set current in step640. In other words, if a measured temperature after charging current isregulated drops below the preset temperature, the wireless powerreceiver may regulate charging current to be increased so that chargingcurrent may be recovered to the level where the measured temperaturedoes not exceed the preset temperature. Otherwise, if the measuredtemperature is higher than the preset temperature in step 660, thewireless power receiver may re-set the charging current in step 670. Instep 680, the wireless power receiver may compare again a measuredtemperature with the preset temperature. If the measured temperature islower than the preset temperature in step 680, the wireless powerreceiver may continue wireless charging with the re-set current in step640. If the measured temperature is higher than the preset temperature,i.e., if a temperature measured after a predetermined interval is stillgreater than the preset temperature, in step 690, the wireless powerreceiver may determine that temperature has not yet been recovered tonormal and may stop wireless charging.

According to various embodiments of the present invention, a wirelesspower receiver may prevent temperature rise by decreasing the current asthe temperature rises above a preset temperature.

Several embodiments have been described in connection with, e.g., mobilecommunication terminals, but a person of ordinary skill in the art willunderstand and appreciate that various modifications can be made withoutdeparting the scope of the present invention. Thus, it will be apparentto those ordinary skilled in the art that the present invention is notlimited to the embodiments described above, which have been providedonly for illustrative purposes.

What is claimed is:
 1. A wireless power receiver for preventingexcessive temperature caused by charging, the wireless power receivercomprising: a power receiver configured to receive wireless power in analternate current (AC) form from a wireless power transmitter; atemperature measurement unit configured to measure a temperature of apoint in the wireless power receiver during reception of the wirelesspower; and a controller configured to decrease a charging powercorresponding to the wireless power, if a temperature measured by thetemperature measurement unit exceeds a preset temperature, and toprovide the charging power to a battery, if the temperature measured bythe temperature measurement unit is lower than the preset temperature.2. The wireless power receiver of claim 1, wherein the point in thewireless power receiver includes at least one component of the wirelesspower receiver.
 3. The wireless power receiver of claim 1, furthercomprising a regulator configured to regulate the wireless power,wherein the controller is further configured to decrease the chargingpower by providing a control signal to the regulator to decrease anoutput current.
 4. The wireless power receiver of claim 3, furthercomprising a rectifier, connected to the power receiver and theregulator, configured to rectify the received wireless power in the ACform into a direct current (DC) form and output the wireless power inthe DC form to the regulator.
 5. The wireless power receiver of claim 4,wherein the temperature measurement unit is further configured tomeasure a temperature of at least one of the power receiver, theregulator, the rectifier, and the battery.
 6. The wireless powerreceiver of claim 1, further comprising a power management unitconfigured to control charging by providing the regulated wireless powerto the battery, wherein the controller is further configured to providea control signal to the power management unit to decrease the chargingpower to the battery.
 7. The wireless power receiver of claim 1, whereinthe controller is further configured to monitor the temperature of thepoint in the wireless power receiver by the temperature measurementunit, if the temperature measured by the temperature measurement unitexceeds the preset temperature, and to repeatedly perform a comparisonof the temperature measured by the temperature measurement unit with thepreset temperature.
 8. The wireless power receiver of claim 7, whereinthe controller is further configured to increase the decreased chargingpower, if the measured temperature is lower than the preset temperature.9. The wireless power receiver of claim 7, wherein the controller isfurther configured to decrease the decreased charging power, if themeasured temperature exceeds the preset temperature.
 10. A method forprotecting a wireless power receiver from excessive temperature causedby charging, the method comprising: receiving wireless power from awireless power transmitter; measuring a temperature of a point in thewireless power receiver during reception of the wireless power;decreasing a charging power corresponding to the wireless power, if atemperature measured by the temperature measurement unit exceeds apreset temperature; and providing the charging power to a battery, ifthe temperature measured by the temperature measurement unit is lowerthan the preset temperature.
 11. The method of claim 10, whereindecreasing the charging power comprises decreasing an output current tothe battery.
 12. The method of claim 10, further comprising:re-measuring a temperature of the point in the wireless power receiverafter decreasing the charging power; and decreasing the decreasedcharging power, if the re-measured temperature exceeds the presettemperature.
 13. The method of claim 12, further comprising increasingthe decreased charging power, if the re-measured temperature is lowerthan the preset temperature.
 14. The method of claim 10, whereindecreasing the charging power comprises providing a control signal todecrease the charging power to one of a regulator for regulating thewireless power or a power management unit for controlling charging byproviding the wireless power regulated by the regulator to the battery.15. The method of claim 10, wherein the point in the wireless powerreceiver includes at least one component of the wireless power receiver.